Its not so much that Bio isn't strong enough....S-gel is actually a pretty strong gel. It is more that it is one of the most flexible gels on the market, and I find that the stress area of a tip doesn't flex as well as the gel and eventually 'gives way' due to stress, whereas if you build your extension with a gel sculpture, then that flexes and moves with the rest of the gel and the nail.
Its kind of like putting a slightly more rigid pole inside a bendy one and bending it - eventually the rigid pole inside will break. The finer and thinner the tip, the better chance you've got of it lasting (I have done the occasional tip with a CND performance tip - but even then i've blended it), but heck its all a lot of trouble whe the Free Edge gel is so so much quicker, easier, cheaper and lasts so much better!